JP5951037B2 - Valve for metering a flowing medium - Google Patents

Description

  The present invention relates to a flowable medium, in particular a valve for metering fluid, according to the superordinate concept of claim 1.

  A known valve of this kind, preferably used as a fuel injection valve (DE 102009026532), comprises a valve housing, an externally opened valve needle with a closing head, and a valve needle. A piezoelectric actuator acting on the valve needle for actuation and a return element acting on the valve needle are provided. For the metered injection of fuel, a metering supply opening (injection opening) arranged in the fuel flow is surrounded by a valve seat, which opens and closes the metering supply opening To work with the closure head. The piezoelectric actuator abuts the end of the valve needle on the side away from the closing head in a force-coupled (coupled manner in which force is transmitted) manner, and the point of action of the return element is the closure of the valve needle Located near the end away from the head. The piezoelectric actuator includes a so-called piezo stack including a piezo module composed of a large number of piezoelectric elements located in contact with each other. The piezo module is clamped between the closing body and the closing plate by means of a hollow body configured as a spring. The return element is a compression coil spring, which is arranged concentrically with respect to the valve needle, on the one hand being fixed at the end of the valve needle facing the actuator On the other hand, it is supported on the valve housing side. When the piezoelectric actuator is energized, the actuator extends and moves the valve needle against the force of the return spring, so that the closed body lifts from the valve seat and opens the metering supply opening. After de-energization, the compression coil spring acting on the valve needle presses the closed body against the valve seat, so that the metering supply opening is closed.

DISCLOSURE OF THE INVENTION A valve according to the invention having the features of claim 1 comprises a piezoelectric actuator that is required when the valve needle is actuated for the required stroke of the closing head by moving the point of action of the return element directly next to the closing head. This has the advantage that the stroke can be set smaller. Since the stroke of the piezoelectric actuator is largely determined by the volume of the piezo stack as an expensive part of the manufacturing technology of the actuator, the volume of the piezo stack and thus the manufacturing cost of the actuator and the valve is reduced as the stroke is reduced. .

  The reduction of the required actuator stroke, while leaving the closing body stroke to open and close the metering supply opening unchanged, is possible at or close to the closing head, as far as the structural circumstances allow. This is achieved by reducing the stroke loss due to the valve needle when the metering supply opening is closed, based on shifting the operating point of the return element. This stroke loss occurs based on the elastic extension of the valve needle when the valve is closed. This extension of the valve needle depends on the return or closing force of the return element, the effective length of the valve needle between the closing head and the point of action of the closing force, the cross-sectional area of the valve needle and the elastic modulus of the valve needle. It depends. By significantly reducing the effective length of the valve needle due to the displacement of the point of action, the stroke loss of the valve needle is smaller and thus the stroke to be additionally exerted from the actuator to the required stroke of the closing head. Becomes smaller.

  By means of the constituent features described in the other claims, suitable improvements and improvements of the valve described in claim 1 are possible.

  According to a preferred aspect of the invention, the displacement of the operating point on the valve needle side of the return element is achieved by the return element comprising a sleeve and a pressing spring that exerts a pressing force directed on the actuator against the sleeve. . The sleeve comprises a sleeve body and a flange projecting radially from the sleeve body and is arranged concentrically with respect to the valve needle, with the end of the return element facing towards the closure head. At the point of action, it is fixedly coupled to the valve needle. The extension of the sleeve that occurs when the valve is closed does not affect the series of actions of the actuator and does not cause any stroke loss due to the valve needle. The sleeve can be manufactured at a low cost as a deep drawing part or a cutting part, and a compression coil spring disposed concentrically with the sleeve body is used as the pressing spring. The compression coil spring is supported in a fixed position with respect to the flange and the valve.

  According to a preferred aspect of the invention, the sleeve body comprises a body section having a smaller diameter and a body section having a larger diameter. The barrel section having a smaller diameter is fitted over the valve needle in a generally shape-coupled manner (coupling based on the mutual geometrical relationship such as mating or meshing), with the end of the free end, At the point of action on the valve needle side, it is welded to the valve needle by the closing head. The flange is integrally formed with the larger diameter cylinder section at the free end face end of the larger diameter cylinder section. This structural aspect of the return element provides a compact and space-saving structural form. The valve needle and the closing body are integrally formed, and the actuator directly contacts the end of the valve needle on the side away from the closing head.

  According to a likewise preferred and alternative embodiment of the invention, the return element is a corrugated bellows, the corrugated bellows at one of the bellows ends at the point of action of the return element on the valve needle side, Secured to the valve needle at or near the closure head and surrounding a push rod that forms a working connection between the valve needle and an actuator located in a valve chamber that is closed in a medium-tight manner, With the bellows end of the valve chamber, the central opening provided for guiding the push rod through the valve chamber toward the actuator is enclosed in a medium-tight manner, so that the operating point on the valve needle side of the return element can be reduced. Displacement is obtained. Thus, the corrugated bellows used to seal the medium-tight valve chamber containing the actuator, known per se, provides an additional function, i.e. a return element for the valve needle for pressing the closing head against the valve seat. It has a function. In this way, the same part is used for sealing and returning the valve needle, thus saving one part. With the introduction of a push rod that aligns with the valve needle, which is in force-coupled contact with the end of the valve needle that enters the corrugated bellows and the actuator, precise force adjustment is possible regardless of the axial rigidity of the corrugated bellows. It becomes possible. Since the length of the push rod is adapted to the corrugated bellows, the corrugated bellows has the desired return or closing force in the assembled state.

  According to one preferred aspect of the invention, the push rod abuts against the actuator and the end of the valve needle away from the closing head, respectively, in a force-coupled manner, in which case the push rod is on the one hand The contact surface between the rod and the valve needle, on the other hand, between the push rod and the actuator is configured as a cardan bearing. By means of a cardan-type shaft support of the push rod, the operation of the valve needle with no lateral force is guaranteed.

  Hereinafter, the present invention will be described in detail based on illustrated embodiments.

It is a longitudinal cross-sectional view of a part of a valve for metering fluid. It is the longitudinal direction sectional view similar to FIG. 1 of another aspect.

  The valve for metering a flowing medium, in particular a fluid, shown in longitudinal section in FIG. 1 is used as an injection valve, for example, for injecting fuel into a combustion cylinder of an internal combustion engine. FIG. 1 shows a longitudinal section at the end of the injection side of the injection valve, in which case the complete valve is shown and described, for example, in DE 102009026532.

  As main components, the valve comprises a metering supply opening 11 arranged in the fluid flow (the metering supply opening 11 is surrounded by a valve seat 12) and a valve needle 13 for controlling the metering supply opening 11. (The valve needle 13 cooperates with the valve seat 12 to close and open the metering supply opening 11 and preferably comprises a closing head 131 formed integrally with the valve needle 13), metering supply A piezoelectric actuator 14 acting on the valve needle 13 for opening the opening 11 and a spring-elastic return element 15 acting on the valve needle 13 for closing the metering supply opening 11 are provided. The piezoelectric actuator 14 is only partially shown in FIG. The piezo actuator 14 comprises, in a known manner, an electrically controllable piezo module or piezo stack, which is connected between the closing plate 17 and the closing body by means of a hollow body 16 configured as a spring. (Also in this regard, see DE 1020090265532).

The cost of the injection valve is largely determined by the piezo stack. In this case, the stroke of the piezoelectric actuator 14 required for the operation of the valve determines the volume of the piezo stack. The volume of the piezo stack itself greatly affects the cost of the piezoelectric actuator 14 due to the use of noble metals for the electrodes. In addition to the stroke required for the defined valve opening of the closing head 131, the piezoelectric actuator 14 must provide an additional stroke to compensate for the so-called stroke loss of the valve needle 13. This stroke loss ΔI of the valve needle 13 due to the closing force acting on the valve needle 13 or the extension of the valve needle 13 based on the returning force of the return element 15 in the closed state of the valve is equal to the closing force F of the return element 15. The effective length I _eff of the valve needle 13 between the closing head 131 (strictly speaking, the surface of the closing head 131 that impinges on the valve seat 12) and the point of action of the return element 15 with respect to the valve needle 13; Depending on the elastic modulus E of 13 and the cross-sectional area A of the valve needle 13,
ΔI = F · I _eff / E · A
become.

  In order to minimize the stroke loss ΔI and thus to reduce the required stroke of the piezoelectric actuator 14 and thus to achieve significant cost savings, as can be seen from FIG. 1, the valve needle side of the return element 15 The point of action 18 is located at the end of the valve needle 13 which supports the closing head 131 or as close as possible to that end. “As close as possible” is understood as “as close as possible in the structural context of the valve”.

  To achieve this, in the embodiment of FIG. 1, the return element 15 comprises a sleeve 19 as well as a pressing spring 20 that exerts a pressing force directed to the piezoelectric actuator 14 on the sleeve 19. The sleeve 19 includes a sleeve body 191 and a flange 192 that protrudes from the sleeve body 191 in the radial direction. The sleeve 19 is arranged concentrically with respect to the valve needle 13 and is fixedly coupled to the valve needle 13 at the point of action 18 of the return element 15 at the end remote from the flange. The sleeve barrel 191 includes a barrel section 191a having a larger diameter that supports the flange 192 on the end side, and a barrel section 191b having a smaller diameter. A barrel section 191b having a smaller diameter is fitted over the valve needle 13 and is mounted on the valve needle 13 in a shape-coupled manner, and at the end of the free end surface on the side away from the flange, 13, which is indicated in FIG. 1 by a weld seam 21. The pressure spring 20 is preferably a compression coil spring disposed concentrically with respect to the sleeve body 191. The compression coil spring is fixed to the valve and supported by the flange 192.

  The aforementioned components of the valve are incorporated in a valve housing 22 and a nozzle body 23 that is fixed to the valve housing 22 and protrudes from the valve housing 22. In the embodiment of FIG. 1, the nozzle body 23 formed of two parts is welded to a hollow cylindrical valve insert 24 welded to the valve housing 22 and an end of the valve insert 24 on the side away from the valve housing. The valve seat support 25 is provided with a valve seat 12 and a metering supply opening 11. The valve needle 13 is guided inside the hollow of the valve seat support 25 by slide rings 26 and 27 spaced apart from each other. Thus, it is pressed against the valve seat 12, in which case the pressing spring 20 configured as a compression coil spring is supported between the flange 192 of the sleeve 19 and the radial shoulder 28 formed in the valve housing 22. Has been. As an alternative or in addition, the supporting point of the pressure spring 20 fixed in position with respect to the valve may be located in the nozzle body 23, ie in the illustrated embodiment in the valve insert 24.

  The piezoelectric actuator 14 having no fuel resistance is disposed in a valve chamber 29 sealed against the medium. The valve needle 13 is introduced into the valve chamber 29 through the central opening 30 to the piezoelectric actuator 14, and abuts against the closing plate 17 of the piezoelectric actuator 14 in a force-coupled manner under the action of the pressing spring 20. . Preferably, the abutment of the end of the valve needle 13 on the side away from the closure head with respect to the closure plate 17 is configured as a cardan bearing. In order to seal the central opening 30 for guiding the penetration of the valve needle 13, a corrugated bellows 34 is provided surrounding the valve needle 13 in the barrel section 191 a of the flange sleeve 19 having a larger diameter. Is fixed to the valve needle 13 in a medium-tight manner with one bellows end and surrounds the central opening 30 in a medium-tight manner with the other bellows end. As can be seen from FIG. 1, the medium-tight valve chamber 29 is formed by a pipe 31 fixed in the valve housing 22, and the pipe end of the pipe 31 on the side facing the nozzle body 23 is a pipe. The medium is tightly closed by an end member 32 fitted into the end. In order to realize the central opening 30 in the valve chamber 29, the end member 32 has a central hole 33, and a slide sleeve 35 is fitted into the central hole 33 in a medium-tight and non-slidable manner. Within the sleeve 35, the valve needle 13 slides. The other bellows end of the corrugated bellows 34 is fixed to the slide sleeve 35. The fixing of the corrugated bellows 34 in the slide sleeve 35 is indicated in FIG. 1 by a weld seam 36, and the fixation of the slide sleeve 35 in the end member 32 is indicated by a weld seam 37, The fixation of the end member 32 is indicated by a weld seam 38. The connection between the valve housing 22 and the valve insert 24 is indicated by a weld seam 39, and the connection between the valve insert 24 and the valve seat support 25 is indicated by a weld seam 40. The medium, i.e. fluid or fuel, is sealed against the medium in the pipe 31 from the inlet shown by the symbol of arrow 41, through a ring gap 43 provided between the pipe 31 and the valve housing 22. Through the radial bore 42 arranged outside the valve chamber 29 and into the nozzle body 23 so that the medium can be present in the closing head 131 under system pressure.

  The valve, a part of which is shown in the longitudinal sectional view in FIG. This valve is different from the previously described valve according to FIG. 1 in that the return element consisting of a flange, a sleeve and a pressure spring is omitted, and the medium into the valve chamber 29 which is sealed against the medium and which houses the piezoelectric actuator 14. In that the corrugated bellows 34 used to seal the ingress of is considered as the return element 15. The metal corrugated bellows 34 is fixed in a medium-tight manner to the valve needle 13 at the operating point 18 of the return element 15 at one bellows end, and to the piezoelectric actuator 14 at the other bellows end. Since it surrounds the central opening 30 of the valve chamber 29 provided for the approach, the corrugated bellows 34 maintains the sealing function in addition to the returning function of the closing head 31 in the embodiment of FIG. The action coupling between the valve needle 13 and the piezoelectric actuator 14 is formed by a push bar 44. The push rod 44 is disposed inside the corrugated bellows 34, and is force-coupled to the end of the valve needle 13 that enters the corrugated bellows 34 on the one hand and the closing plate 17 of the piezoelectric actuator 14 on the other hand. That is, it is supported so that force can be transmitted. Both supports are preferably configured as cardan bearings, so that the valve needle 13 can be operated without application of lateral forces. Since the length of the push bar 44 is adapted to the corrugated bellows 34, in the assembled state, the desired closing or returning force of the spring-elastic corrugated bellows 34 is generated on the valve needle 13.

  As in the case of the valve according to FIG. 1, the valve chamber 29 for accommodating the piezoelectric actuator 14 is formed by a pipe 31 fixed in the valve housing 22, and the pipe end of the pipe 31 on the side facing the nozzle body 23. The portion is closed in a medium-tight manner by an end member 32 having a center hole 33 fitted into the tube end. Unlike the case of the valve according to FIG. 1, the end member 32 is integrally formed with the valve insert 24 ′ of the nozzle body 23, rather than as a separate component. The medium-tight joint between the tube 31 and the end member 32 is also formed by a weld seam 38. Similarly, a slide sleeve 35 is fitted into the center hole 33 of the end member 32, and the slide sleeve 35 is coupled to the end member 32 in a fixed position by a welding seam 37. The end of the corrugated bellows 34 that closes the center opening 30 in a medium-tight manner is fixed in a medium-tight manner to the slide sleeve 35 by a weld seam 36, and the push rod 44 is accommodated in the slide sleeve 35 so as to be movable in the axial direction. ing. The medium flow in the valve housing 22 is provided from the medium inflow portion indicated by the arrow 41 to the valve insert 24 ′ of the nozzle body 23 via a ring gap 43 provided between the valve housing 22 and the pipe 31. The valve needle 13 and the closing head 131 are reached through the formed radial hole 46.

Claims (10)

A metering supplying valve with flow medium body,
A metering supply opening (11) surrounded by a valve seat (12), disposed in the fluid flow;
A valve needle (13) for controlling the metering supply opening (11), a closing head (131) cooperating with the valve seat (12) to close and open the metering supply opening (11). A valve needle (13) having
A piezoelectric actuator (14) acting on the valve needle (13) to open the metering supply opening (11);
A spring resilient return element (15) acting on the valve needle (13) to close the metering supply opening (11);
A valve for metering a flowing medium, comprising:
An operating point (18) on the valve needle side of the return element (15) is located at or near the end of the valve needle (13) with the closure head (131) ;
The return element (15) comprises a sleeve (19) and a pressing spring (20) that exerts a pressing force directed to the piezoelectric actuator (14) on the sleeve (19), the sleeve (19) comprising: Concentrically arranged with respect to the valve needle (13), the end of the sleeve (19) facing the closing head (131) is the point of action of the return element (15). It is fixedly connected to the valve needle (13),
The sleeve (19) includes a sleeve body (191) and a flange (192) protruding radially from the sleeve body (191), and the pressing spring (20) is a compression coil spring, The compression coil spring is disposed concentrically with the sleeve body (191) and supported by the flange (192);
The valve seat (12) and the metering supply opening (11) are formed in a nozzle body (23), and the nozzle body (23) includes the valve needle (13), the piezoelectric actuator (14), and the like. The pressure spring (20) fixed to the valve housing (22) that houses the return element (15) and supported by the flange (192) further comprises the nozzle body (23), and / or Supported on a radial shoulder (28) formed in the valve housing (22);
A valve for metering a flowing medium, characterized in that the working point (18) is located between the radial shoulder (28) and the end with the closing head (131) . The sleeve body (191) comprises a body section (191b) having a smaller diameter and a body section (191a) having a larger diameter, the body section (191b) having a smaller diameter comprising the valve needle. (13) The flange is mounted on the free end surface end of the trunk section (191a), which is mounted on and welded to the valve needle (13) with a free end surface end. (192) is integrally molded, claim 1 valve according. The valve needle (13) and the closing head (131) are integrally formed, and the piezoelectric actuator (14) is attached to the end of the valve needle (13) on the side away from the closing head. the force binding equation in contact, according to claim 1 or 2 valve according. The piezoelectric actuator (14) is arranged in a valve chamber (29) sealed against the medium, and the valve needle (13) is introduced into the valve chamber (29) through a central opening (30). A corrugated bellows (34) surrounding a part of the valve needle (13) is fixed in a medium-tight manner to the valve needle (13) with one bellows end, and the other bellows end with in parts, it surrounds a central opening (30) communicating with the valve chamber (29) in medium-tight, any one valve as claimed in claims 1 to 3. The valve chamber (29) is formed by a pipe (31) fixed in the valve housing (22), and a pipe end of the pipe (31) facing the nozzle body (23). Is closed in a medium-tight manner by an end member (32) having a central hole (33) fitted in the pipe end, and the central opening (30) for guiding the valve needle (13) to pass therethrough. ) Is realized by a slide sleeve (35) for guiding the valve needle (13) fixed in a medium-tight manner in the central hole (33) of the end member (32), and the slide sleeve (35). The valve according to claim 4 , wherein the other bellows end of the corrugated bellows is fixed. A valve for metering a flowing medium,
A metering supply opening (11) surrounded by a valve seat (12), disposed in the fluid flow;
A valve needle (13) for controlling the metering supply opening (11), a closing head (131) cooperating with the valve seat (12) to close and open the metering supply opening (11). A valve needle (13) having
A piezoelectric actuator (14) acting on the valve needle (13) to open the metering supply opening (11);
A spring resilient return element (15) acting on the valve needle (13) to close the metering supply opening (11);
A valve for metering a flowing medium, comprising:
An operating point (18) on the valve needle side of the return element (15) is located at or near the end of the valve needle (13) with the closure head (131);
The piezoelectric actuator (14) is arranged in a valve chamber (29) sealed against the medium,
The return element (15) is a corrugated bellows (34), and the corrugated bellows (34) has one bellows end as an action point (18) on the valve needle side of the return element (15). Action between the valve needle (13) and the piezoelectric actuator (14) disposed in the valve chamber (29) which is fixed to the valve needle (13) in a medium-tight manner and sealed against the medium. The push rod (44) forming the coupling portion is surrounded, and the other bellows end portion is used to guide the push rod (44) through the valve chamber (29) toward the piezoelectric actuator (14). A valve for metering a flowing medium, characterized in that the central opening (30) provided for the purpose is enclosed in a medium-tight manner. The push rod (44) is in contact with the piezoelectric actuator (14) and an end of the valve needle (13) that projects into the push rod (44), respectively, in a force-coupled manner. 6. The valve according to 6 . On the one hand, the contact part between the push bar (44) and the valve needle (13) and on the other hand between the push bar (44) and the piezoelectric actuator (14) is configured as a cardan bearing. The valve according to claim 7 . The valve seat (12) and the metering supply opening (11) are formed in the nozzle body (23),
The valve chamber (29) is formed by a pipe (31) fixed in the valve housing (22), and the pipe end of the pipe (31) facing the nozzle body (23) is , And is closed in a medium-tight manner by an end member (32) fitted in the tube end and having a central hole (33), and the central opening (30) for the valve needle (13) It is realized by a slide sleeve (35) for guiding the push rod (44) fixed in a medium-tight manner in the center hole (33) of the end member (32), and the corrugated wave is formed on the slide sleeve (35). 9. Valve according to any one of claims 6 to 8 , wherein the other bellows end of the bellows (34) is fixed. The valve according to claim 9 , wherein the end member (32) is integrally formed with the nozzle body (23).

Images